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ABSTRACT
Porcine reproductive and respiratory syndrome (PRRS) is a globally prevalent contagious disease caused by the positive-strand RNA PRRS virus (PRRSV), resulting in substantial economic losses in the swine industry. Modifying the CD163 SRCR5 domain, either through deletion or substitution, can eff1 ectively confer resistance to PRRSV infection in pigs. However, large fragment modifications in pigs inevitably raise concerns about potential adverse effects on growth performance. Reducing the impact of genetic modifications on normal physiological functions is a promising direction for developing PRRSV-resistant pigs. In the current study, we identified a specific functional amino acid in CD163 that influences PRRSV proliferation. Viral infection experiments conducted on Mard 45 and PK-15CD163 cells illustrated that the mE535G or corresponding pE529G mutations markedly inhibited highly pathogenic PRRSV (HP-PRRSV) proliferation by preventing viral binding and entry. Furthermore, individual viral challenge tests revealed that pigs with the E529G mutation had viral loads two orders of magnitude lower than wild-type (WT) pigs, confirming effective resistance to HP-PRRSV. Examination of the physiological indicators and scavenger function of CD163 verified no significant differences between the WT and E529G pigs. These findings suggest that E529G pigs can be used for breeding PRRSV-resistant pigs, providing novel insights into controlling future PRRSV outbreaks.
Keywords: PRRSV; CD163; Point mutation; E529G; Pigs
INTRODUCTION
Porcine reproductive and respiratory syndrome (PRRS), commonly known as pig blue-ear disease, is caused by the PRRS virus (PRRSV) (Lunney etai., 2016). This contagious disease is characterized by reproductive disorders in pregnant sows and respiratory disease in pigs of all ages, particularly piglets (Ma et al., 2021b). PRRS has become one of the most economically devastating diseases affecting the swine industry worldwide (Holtkamp etai., 2013; Renken etai., 2021). While current prevention and control methods, such as vaccine immunization, are somewhat effective (Kick etai., 2023), challenges remain in overcoming the virus's immune escape mechanisms, recombination diversity, and antibodydependent enhancement.
Research has identified CD163 as a crucial host factor for PRRSV, serving as a specific and indispensable receptor for viral entry and uncoating (Calvert et al., 2007; Van Gorp et al., 2008; Welch & Calvert, 2010; Yu etai., 2020). Advances in CRISPR/Cas9 technology have made gene editing more feasible, offering potential solutions for eradicating various diseases through genetic modification (Jiang & Doudna, 2017). Specifically, CD163 gene...